1. Field of the Invention
The present invention relates to an image reading apparatus for reading radiation image information recorded on a radiation image recording medium that is held in a cassette and thereafter erasing radiation image information remaining on the radiation image recording medium.
2. Description of the Related Art
There has heretofore been known an image reading apparatus employing a stimulable phosphor sheet which, when exposed to an applied radiation, stores part of the energy of the radiation, and, when subsequently exposed to applied stimulating rays such as visible light, emits light in proportion to the stored energy of the radiation.
The image reading apparatus includes a cassette loader for loading a cassette storing a stimulable phosphor sheet which records therein radiation image information of a subject such as a human body, a reader for applying stimulating light to the stimulable phosphor sheet removed from the cassette to read the radiation image information from the stimulable phosphor sheet, and an eraser for applying erasing light to the stimulable phosphor panel from which the radiation image information has been read to erase remaining radiation image information from the stimulable phosphor sheet. The removed stimulable phosphor sheet from which the remaining radiation image information has been erased is returned into the cassette and then discharged, while being stored in the cassette, out of the image reading apparatus to be used again.
One such image recording apparatus is disclosed in Japanese Laid-Open Patent Publication No. 11-160817. According to the disclosed image recording apparatus, a plate holder for holding a stimulable phosphor plate is disposed substantially vertically in the image recording apparatus, and a reader for reading radiation image information and an eraser for erasing remaining radiation image information are disposed in parallel with each other in confronting relation to the plate holder. The stimulable phosphor plate is fed along the plate holder to a position facing the reader, in which the reader reads the radiation image information recorded in the stimulable phosphor plate. Thereafter, the stimulable phosphor plate is delivered to a position facing the eraser, in which the eraser erases the remaining radiation image information from the stimulable phosphor plate.
Japanese Laid-Open Patent Publication No. 2002-156716 discloses an image reading apparatus having a cassette inserter and discharger which is inclined at a certain angle on a side panel of an apparatus casing. When a cassette is loaded in the cassette inserter and discharger, a frame of the cassette is removed, and an exposed stimulable phosphor sheet stored in the cassette is fed by a feed means into the apparatus casing. Thereafter, the stimulable phosphor sheet is fed vertically upwardly by an auxiliary scanning means disposed in the apparatus casing. A reading means that is disposed along the auxiliary scanning means then reads radiation image information recorded in the stimulable phosphor sheet. Remaining radiation image information is subsequently erased from the stimulable phosphor sheet by an erasing means that is disposed below the reading means.
In the image reading apparatus disclosed in Japanese Laid-Open Patent Publication No. 11-160817 and Japanese Laid-Open Patent Publication No. 2002-156716, the reader for reading radiation image information and the eraser for erasing remaining radiation image information are vertically disposed in parallel with each other, and the stimulable phosphor plate or sheet is fed vertically along the reader and the eraser. Therefore, the stimulable phosphor plate or sheet needs to be fed along a long vertical feed path in the apparatus casing, which necessarily makes the image reading apparatus large in vertical dimension.
There has been a demand in the art for quick and efficient processes for reading and erasing radiation image information from stimulable phosphor sheets in image reading apparatus.